In a coin hopper which dispenses coins one by one using a rotary disk disposed on a lower portion of a cylindrical storing bowl, various kinds of techniques have been proposed to detect an amount of coins remaining in the storing bowl.
JP-A-07-1600919 (see FIG. 1, Pages. 3 to 4) presents an example of a first conventional practice or state of the art. A device is provided in which a pair of electrodes is mounted on a side wall of the storing bowl. When these electrodes are not electrically conducting as to each other via stored coins having conductivity, a coin empty signal is output. In other words, when enough coins are stored in the storing bowl, the pair of electrodes conduct as to each other through conductive coins. However, when a coin retaining amount is reduced, the pair of electrodes is not conductive as to each other by the conductive coins, the coin empty signal is output.
JP-A-63-24389 (see FIG. 2, Pages. 2 to 3) presents features of a second conventional practice from the prior art in which a flexible electrode is fixed on a wall face of a storing bowl. A metallic base, on which a coin that drops through a through-hole of a rotary disk slides, is constituted as an electrode paired with the flexible electrode. When these electrodes are not electrically conductive as to each other, an empty signal is output.
JP-A-63-29894 (see FIG. 1, Page. 2) presents features of a third conventional practice from the prior art, which uses a photoelectronic sensor whose optical axis is disposed in a crossing manner just above an upper face of a rotary disk.
According to what is disclosed in JP-A-07-1600919, since the pair of electrodes is fixed on the side wall of the storing bowl, these electrodes must be disposed separately from each other by a predetermined distance or more, and since the pair of electrodes is disposed above the rotary disk, the empty signal is output in a state in which a remaining coin amount is relatively large, so that there is a problem that a coin replenishing interval is shortened.
According to what is disclosed in JP-A-63-24389, since coins are detected when the flexible electrode, which can enter the through hole of the rotary disk and the base on which a coin slides, are conductive as to each other by coins, and the empty signal is output when they are not conductive as to each other via coins, there is an advantage that the empty signal can be output in a state in which a remaining coin amount is small. However, this cannot be applied when a base is a non-conductive material such as resin.
According to what is disclosed in JP-A-63-29894, since the optical axis for the remaining coin detection must cover a certain detection range, a plurality of photoelectronic sensors must be disposed, which results in a high price. As such, this is difficult to be adopted readily. Further, when the photoelectronic sensor is used, there is a problem that such maintenance as cleaning a light projecting and receiving face periodically is required.